Patent Document 1 describes a vehicle seat with a dynamic damper configured by a mass body integrally supported inside a pad. Patent Document 2 below describes a headrest with a dynamic damper configured by a resilient resin material that is injected and foamed inside a mold envelope, and a weight that is disposed fixed inside the mold envelope. This related art enables noise and vibration performance (NV performance) to be improved since the dynamic dampers attenuate oscillation.